I tried this. First, changed the Avira account from german into english. Then you would see the trial subscription free for one year, and you could get the english version by pressing the install button on the right.
I'm in the USA. I received the link to download in my email, installed german version. After install Avira website popped up, changed language in my profile to English, unistalled German version, downloaded installer again and now it's in English with a full year. Fastest VPN I ever used!
Go to Avira site > Device > Android > Phantom VPN > Send it to your email after this than check your email on your tablet so you can download it from there. i think you have to login into avira on the tablet..